Gun sight having a plurality of illuminated reticles



Nov. 16,1948. H. BROWN 5 sun sxeaw HAVING A PLURALITY OF ILLUMINATED RETICLES Filed March 17, 1944 2 Sheets-Sheet 1 Figu'ln L513 ILEIRUWN,

' Filegl March-l7; 1944- NOV. 16, 1948. BROWN 2,453,697

GUN SIGHT HAVING A PLURALITY OF ILLUMINATED RETICLES 2 Sheets-Sheet 2 'Fl gdl'lL 4 15 12.

"ff n a2 aamwfimw tailed'description below-of embodiments of Patented Nov. 16, 1948 GsF- FICE i-GUN sierra navmomenunam'ryxor reLUMiNA'ren REEI'ICLES Leo H. Brown, Glenvill'e, Conn.

Application March 17, 1944,. Serial bio/526,956

I 2 lClaims.

(Granted under the The invention described hereinmay be manufactured and used by or iorthe' Government for governmental purposes,-without the payment to s ne of anyroyalty thereon.

This invention relates to sights'for guns. .Among the objects of the invention is the provision of-a reflector sight in which a large exit pupil maybe obtained with a colli nating lens or :lens system of small Another object of'the invention is to provide aperture.

a reflex sight Whose exit-pupilis many times the area of the-aperture of'the collimating lens or collimating lens-sy'stem, or many 'tirnes the area of that part of thecollimating lens or lens system=through which light from-the reticle'is allowed tc-pass.

Still anotherbbject o'i the-invention is the provision ofa collimator gunsight which avoidsthe necessity of 'usinglarge collimating lenses to obtain a large exitpupil or field of observation.

' A further object of th'einvention is the pro- -vision of-a reflecting collimator sight forguns which is compact ineonstructi'on, and which may be symmetrical with reference to three axes at right anglesto each other.

A further" object of the invention isto provide means for apportioning a quantity of light over an area'in several steps, without dispersion or substantial dispersion thereof.

Other obj ects-will be .appreciated'f rom .the dethe invention.

In the accompanying drawings which illustrate several examples of gun sights constructed: in accordance with the present invention:

Figure-l shows in 'perspeetivez the external appearance of one modification ofrthe gun'sight and 'how it is use'din sighting on aitarget.

Figure 2 is a vertical cross1section of. the gun sight on the line Z 2 'ofFigure 1 with certain of the parts in elevation.

Figure? is aviewspartly'in front elevation and partly in section on thelinet3-3 :of :Figure-Z.

'Figure 4'is across. section'similarxto Figure 2 of another modification of 'the invention and taken on theline- L-A of'Figure-5.

Figure 5. is a vertical section: take onthe line "5-5 :oi Figure 4.

Figure 6* is la horizontal section taken on the line 6-45 of "Figurerfi.

act

i'ngfi is placed i6, and ii. prisms and I3, 14-; i5, and lfi -are parallelepipeexcept the pair'consisting of "prisms formed a mirror of silver or of aluminum :which light, in degrees or 'p 'in detail hereinafter. A full or opaque niirroris, however, formed'on one of "of l6 and IT forming the interface 2'4.

of March 3, 1=883,-.-as- .amendeclApril'30, 1928.; 370 0. G- 757) cross section, and "in Wvhich the collimating 'lenses 2, *3, reflecting'prism 4', electric-light bulb 5,

andli'ght bulb housing 6 are-mounted. Electric "bulb-'5 is"enclosed"withimtl're-housing 6 provided with an aperture "Tover'which is placed the slide *8, WhiGh'lS carried in" guides "9, 9 secured to the housing 5. A retic'le is placed upon the slide'8 for illuminationbylight from the light bulb 5. The housing 6 is secured-to the-casing inany "suitable waygand'preferably detachably. A reflector lflis"so -disposed in-relation to'the light bulb that light emitted by the bulb is directed-to- Wards'thereticle on'slide 8L '-Slide"8 is-removable fromthe guides 9 toenable replacement or-substitution of 'reticles.

Above the collimating lenses- 2; 3 and the housa row of glass prisms l2, l3, l4, l5, Prisms H and l"! e are triangular dons. These prisms serially abut one against the other and are so-shaped asto provide-planes or interfacesofabutmentill zl, 22.23, and 24 that are inel-inedatsubstantially 45 to-the-longitudinal axis of the 'rowof -prisms. 'Onone of the abutting surfaces of each pair of abutting prisms, lfiandl'l, is

partially transmits light and'partially reflects ercentages described more the" abutting surfaces The prisms'l2,-l3;- l4, 5.16, andll, afterthe formation-of said mirrors, are cemented togetherewith Canada balsam", so that there is a partially silvered mirror at eachofthe interfaces 120, 2!,22, ancl'2 3", and a fully silvered mirror at interface. 24. These mirrors which are parallel and inclined at 45? to the-optical or longitudinalzaxis of the assembly are designated as mirrors $1, 32, 33; 34 and *35.

Directly above theprisms122,.I3, M, [5, and i6 is positioned. a eolurnn or row-of prisms 36,31, '38, 3-9 and IQ-which abut one against the other to provide parallel and'inclined planes orinterfaces 4 l 42, $3 and M. Prisms ISaiand 14B are-triangularprismswhile prisms131,38 and. 39' parallelepipe'dons. 'These-prisms-are provided between their abutting surfaces, on one surface .of each pair of abutting surfaces, witha mirror of silver-or of aluminum whichxpartially transmits. andxpartially reflects light. eachrtot'thea extent hereinafter described.v The'prisms, after 'silvering, are .eemerited together with Canada balsam;- w'lheiinclination of'gtheeabutting faces or mirrors .is such is so silvered as to reflect 33 light incident upon mirror as to form an angle of 45 with the optical axis of the column or row. For the purposes of reference these mirror surfaces are indicated by numerals 5|, 52, 53 and 54.

At one side of the column of prisms 36, 37, 38, 33 and 40, is positioned a transparent glass plate 51 and a similar plate 58 is positioned on the opposite side of the said column. The said glass plates extend into the casing and also comprised between them are prisms l2, |3, |4, |5, I6 and H. The plates 57 and 58 are cemented with Canada balsam to prisms 36, 31, 38, 39, and 40 and to prisms |2, |3, l4, l5, I6, and I1, whereby the said prisms and the said plates constitute a unit which is insertable in casing I above the collimating lenses 2 and 3 and lamp housing 6.

Collimating lenses 2 and 3 and prism 4 are seccured in casing below the prism l3, so that the light emerging from the lenses 2 and 3 is incident upon the first partial mirror 3| Slide 8 and the reticle thereon is so positioned with relation to the collimating lenses 2 and 3 that the length of the optical path from the reticle to the collimating lenses is equal to the focal length of the lens combination consisting of lenses 2 and 3, whereby the light rays from the reticle after emerging from the collimating lenses are substantially parallel.

As appears in Figure 3, reflecting prism 4| is so positioned that light from the reticle or slide 8 isreflected into-the collimating lenses, or lens combination. I

The characteristics of the various mirrors which partially reflect andpartially transmit light are now described. Thetotal quantity of the light emerging from the collimating lenses is taken at 100%. Mirror 3| is so partially silvered as to transmit of this total upwardy to prism l2, whence it emerges and enters into prism 36. The remaining 80% is reflected towards the mirror 32 which is so silvered as to vreflect thereof, or 20% of the original light, upwardly into prism 36. The 60% of the original light which remains is transmitted to mirror 33 which or 20% of the original light, upwardly into prism 36 and to permit 40% of the original light to be transmitted to mirror 34. Mirror 34, in turn, is so silvered that it reflects 50% of the light incident thereon, or 20% of the original light, upwardly into prism 36. The remaining 20% of the original light'which is transmitted through mirror 34 proceeds to mirror 35 from which 100% of it, or 20% of the original light, is reflected upwardly into prism 36. The mirror 36 is, therefore, a fully silvered mirror.

It is'to be noted that each of the five mirrors 3|, 32, 33, 34 and 35 is so silvered as to direct upwardly into prism 36,'20% of the 100% of light emerging from the collimating lenses 2 and 3. In this manner the parallel rays of light which diverged from the reticle are uniformly apportioned along the length of prism 36 and apportioned uniformly on mirror'5i. Thus, the five inclined mirrors 3|, 32, 33, 34, and 35 constitute means for apportioning a given quantity of light uniformly over an area, such as a reflecting surface 36, Without the occurrence or substantial occurrence of dispersion. This apportionment of the light may be considered as first occurring over a plane intersecting the planes of mirrors 3|, 33,

33,34 and 35 at an angle at 45.

=The sum of five 20% portions of the original 5| now make up the 100% of the said 60%,,

"quantity of light which emerges from the collimating lenses" 2 and 3, neglecting, for the purpose of simplifying the description, absorption or losses which may have occurred.

New mirrors or mirror surfaces 5|, 52, 53 and 54 are so silvered as to partially reflect and partially transmit light incident thereon. Mirrors 5|, 52, 53, and 50 are each so silvered as to reflect a fraction of the total light entering prism 36 and to transmit the remainder. Such a reflected portion may be, for example 10% of the quantity of light entering prism 35. Thus, when said 10% is reflected by each mirror, each of said four mirrors must reflect respectively 10%, 11.1%, 12.5% and 14.3% of the percentage of the original light incident thereon. Thus inclined mirrors 5|, 52, 53 and 54 constitute means for apportioning a quantity of light without dispersion or substantial dispersion, over a plane, represented by the plane of plate 51 which is at an angle of 45 with the planes of the mirrors 5|, 52, 53 and 54 in the illustrated embodiment of the invention.

The 60% of the total of the light which enters prism 36, which is not reflected by mirrors 5|, 52, 53 and 54! is transmitted upwardly out of the prism 50 or absorbed in a black coating applied to the top thereof,

The silver or aluminum coatings of mirrors 5|, 52, 53 and 54 must be thin enough to enable the target to be seen therethrough when looking through the device as shown in Figure 1 when the plate 51 faces the observer.

Operation.-'Ihe broken lines with arrow heads applied thereto indicate the path and apportionment of a pencil of light rays starting at the reticle on slide 8, and which enters collimating lens combination 2, 3, symmetrically with respect to the principal axisv of the said collimating lens combination. The pencil after passage through the collimating lens combination is constituted of parallel rays of light. The parallel rays are first incident upon the mirror 3|, and thereafter subsequently pass through each of partial mirrors 32, 33 and 34 and finally on to full mirror 35. At mirror 35, 20% of the total quantity of the light in the pencil is transmitted upwardly into prism l2 and then into prism 36, and at each of mirrors 32, 33, 3'0 and 35, 20% of the total quantity of light in the original pencil is apportioned and reflected upwardly into prism 36.

. The light which emerged from the collimating lens combination 2, 3 has now been spread out and apportioned uniformly in a direction parallel to its direction of propagation. The light now proceeds in succession to and through mirrors 5|, 52, 53 and'5 l which each apportion it by partial reflection and partial transmission, so that the light now becomes spread out and apportioned as indicated by the arrow heads 59 in Figure 2 in a direction at right angles to the direction in which it was spread out by mirrors 3|, 32,

' 33, 34 and 35, or over an area, for example, on

the plane of plate 57, forming an angle of 45 with the planes of mirrors 5|, 52, 53 and 54.

Referring now specifically to the modification illustrated in Figures 4, 5 and 6, the numeral 60 indicates a casing in which the various prisms and lenses are assembled. This casing is provided with a removable cover portion 6| at one end to permit insertion of the various elements within the casing. The upper part of the casing is open at both sides to provide opposite Windows 62 and 63.

A number of square converging collimating lenses are arranged in a row across the casing 60. Four of such lenses are illustrated in Figure 5 and gent est 5. indicated therein by numerals 64, 65, 66 and '61. These :lenses are-positionedtin-thecasing ta below the windows 62 and 63 and areheld therein in any suitable manner.. The, converging. lenses are contiguous and substantially in" the s'ame plane, with theirzprincipal axes substantially parallel.

triangular reflecting, prism.-ii'8 is secured in suitable. manner in the, casing 60 belowfthe Iens'esfil, 6:5 66 and. S1,. and thereflecting; surfiace of 'saida-prisrn. is of. suflicient extentito reflect; light incident thereontolallfour ofjsaidtlense's; Prism advantageously located znear the bottom of casing 60 andpissecured-.ever tour openings 69 therein. The distance between the centers of these openings is equal tethe -distance between the centers of the four collimating lens es, whereby a an opening 1 correspondingto each lens is pro- Four reticleplateslfl arecemented with Canada balsam on the face of prism 68 that covers the openings 69, each plate being cemented on said face to register with one of said openings. Each plate 10 carries a reticle, each reticle being so located that light from the center thereof enters its corresponding collimating lens substantially along its principal axis. The reticles preferably lie in the interface formed by each plate In and prism 68.

A light housing ll covers the openings 69 as shown in Figure 4, and is provided with flanges 12 which engage and slide in guides 13 to enable the light housing to be removed from casing 60, whereby solar light may be used to illuminate the reticles on reticle plates 10, when it is possible to employ this form of illumination.

Light housing l I carries four electric light bulbs I4 which register with the four openings 69. A reflector I5 is provided for each light bulb. These lights provide illumination for the reticles on plates when solar or daylight illumination is not used.

Four or more glass prisms 8!, 82, 83 and 84 ex tend across the casing 66 above the four collimating lenses 64, 65, 66 and B! and are arranged as a column or row in the same Way that the prisms 36, 31, 38, 39 and 40 are arranged in the modification illustrated in Figures 1, 2 and 3. They are cemented together in the same way as the latter and in the interfaces B5, 86, 81 are provided mirror coatings or surfaces which both reflect and transmit light. These mirrors are indicated by the numerals 9!, 92, and 93. However, in the modification of the invention illustrated in Figures 4, 5 and 6, the coatings of silver or aluminum have been so applied to the prisms as to give percentages of light reflectance and light transmission which are different from those given in connection with the modification illustrated in Figures 1, 2 and 3. Thus, in the modification illustrated in Figures 4, 5 and 6, there are three inclined reflecting mirrors 9], 92 and 93 with the following light reflecting and light transmitting characteristics: mirror 9! reflects 33 /3% and transmits 66 /37?) of the light incident thereon; mirror 92 reflects 50% and transmits 50% of the light incident thereon; and mirror 93 reflects 100% and transmits zero percent of the light incident thereon. Therefore, taking the light which enters prism 8| as 100%, 33 /s% of it is reflected at each of mirrors 9|, 92 and 93, as indicated by the dotted lines 94, 95, and 96. These mirrors are inclined in the same way and to the same extent as the mirrors in the modification illustrated in Figures 1, 2, and 3.

The length of the optical path from each reticle on the reticle plates 10 to the collimating lenses 643- 65 '66-, and or is equal to thefocal length of thesel'enses, whereby the light rays which pro ceed fromthe retic1es to the" said' lenses emerge substantialiy parallel from the latter. r

In the modi fi'cation of'the invention illustrated in Figure? the simultaneously lighttransmitting and light reflecting mirrors are carried'oninclined glass plates 'i fiil:instead ofbeing posi tionedin interfaces between prisms as in Figure 4'. A plurality of collimating'lenses is also em pl'oyed as in the-modificatibri illustrated in Figures, and 6; one-of the lensesbeihg indicated by the'numeral I01 'in Figure'l'. A reticle is located onreti'cl'eplate H32 which is illuminated by an-electric light illa' provided with reflector H141 The reticle plate i512, light 103 and reflector NM are contained within a housing Hi5 secured to casing 'lllB. Casing F06 corresponds to casing 60 of the modification illustrated in Figures 4, 5-and '6, and housing I coversthe opening l'llfin'thewall of said casing through which light passes from the reticle on'plate" I02 toi-nclined mirro lflii at the bottom of casing H16. There is a light and reticle for each collimating lens NH. The inclination of the mirrors on inclined plates is the same as in the other modifications described above. Plates We are secured on brackets H39 carried on each end N0 of easing I06. Windows III and H2 are provided in the casing I 06 above the collimating lenses, and correspond to windows 62 and 63 of the modification illustrated in Figures 4, 5 and 6.

In the modifications illustrated in Figures 4 to '7 inclusive, light proceeds from the reticles to the collimating lenses and then to the inclined simultaneously light transmitting and light refiecting surfaces 9!, 92 and 93 (of the modification illustrated in Figures 4, 5 and 6) and to the simultaneously light transmitting and reflecting surfaces on plates I00 (of the modification illustrated in Figure '7) Iclaim:

1. In a gun sight, a reticle, collimating means for rays of light from said reticle, a plurality of prisms arranged in a row in abutting relation ship to provide a plurality of pairs of abutting surfaces inclined at substantially forty-five degrees to the longitudinal axis of the row, a mirror surface which partially transmits and partially reflects light positioned between each of said pairs of abutting surfaces, said collimating means being so disposed with relation to the first of said mirror surfaces that axial light rays passing from said collimating means are incident upon the first of said mirror surfaces at substantially forty-five degrees; a second plurality of prisms arranged in a row in abutting relationship also to provide a plurality of pairs of abutting surfaces inclined at substantially forty-five degrees to the longitudinal axis of the row, a mirror surface which partially transmits light and partially reflects light between each of said pairs of abutting surfaces, said second row of prisms being so positioned with respect to said first row of prisms that the mirror surfaces in said second row will receive at an angle of'incidence a substantially forty-five degrees axial light rays from said collimating means reflected by the mirror surfaces in said first row of prisms.

2. In a gun sight, a reticle, collimating means for rays of light from said reticle, a plurality of parallelepipedons arranged in a row in abutting relationship to provide a plurality of pairs of abutting surfaces inclined at substantially fortyfive degrees to the longitudinal axis of the row,

a mirror surface which partially transmits light and partially reflects light positioned between each of said pairs of abutting surfaces, said collimatin means being so disposed with relation to the first of said mirror surfaces that axial light rays passing from said collimating means are incident upon the first of said mirror surfaces at substantially forty-five degrees; a second plurality of parallelepipedons arranged in a row in abutting relationship also to provide a plurality of pairs of abutting surfaces inclined at substantially forty-five degrees to the longitudinal axis of the row, a mirror surface which partially transmits light and partially reflects light between each of said pairs of abutting surfaces, said second row of parallelepipedons being positioned with respect to said first row that the mirror surfaces in said second row will receive at an angle of incidence of substantially forty-five degrees axial light rays from said collimating means reflected by the mirror surfaces in said first row of parallelepipedons.

. LEO H. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

